Conventionally, as a nonaqueous electrolyte secondary battery, there has been known a nonaqueous electrolyte secondary battery described in JP-A-2012-230905, for example. In this nonaqueous electrolyte secondary battery, an energy storage element is housed in the inside of an outer can. The outer can has an opening and the opening is sealed by a sealing plate. External electrode terminals are mounted outside the sealing plate, and project outward from the sealing plate. Current collecting tab members are electrically connected to the energy storage element. A diaphragm is disposed on a battery inner side with respect to the sealing plate and on a battery outer side with respect to the current collecting tab members. The diaphragms are electrically connected to the external electrode terminals.
The external electrode terminal and the diaphragm are electrically connected to each other by a sealing body lead. A first insulating member (insulating plate) is interposed between the sealing plate and a sealing body lead. A second insulating member (current collecting tab holder) is interposed between the diaphragm and the current collecting tab member.
The second insulating member has a through hole, and the diaphragm and the current collecting tab member are connected to each other through the through hole.
The diaphragm is configured such that when an internal pressure of a battery is increased, the diaphragm is deformed toward the battery outer side. Due to deformation of the diaphragm, the connection between the diaphragm and the current collecting tab member breaks so that an electric current which flows between the diaphragm and the current collecting tab member is cut off.